What series do you think should have more doujinshi/hentai?

to aru majutsu no index- gotta have more Misaka!

Kanokon
High School of the Dead
Ore no Imouto
Seikon no Qwaser

Hayate no Gotoku (Nagi)

MOAR MISAKA. She is very kawaii ^^

To love ru
Fullmetal Panic
Cowboy beebop
rosario vampire
love hina
oh my goddess
HEY ARNOLD

-Ga-Rei
-Gantz
-Mahoromatic
-Maburaho
-Mahoraba
-Girls Bravo
-K-on
-Fairy Tail
-Karin
-School Rumble
-Higurashi no naku koro ni
-Kanokon
-Kiss X Sis
-Rosario Vampire
-Fate/Stay Night
-Shakugan no Shana
-Air Gear
-Ikkitousen
-Tenjou Tenge
-Soul eater
-Amagami SS
-True Tears
-School Days
-Tsukihime

Id like to see more Strike Witches hentai

Sankarea. I find that the lack of GuroVanilla is quite disappointing.

One Piece.
Women in O-Piece have a peculiar art that looks so arousing to me.

Deadman wonderland. I had an incredible urge to find some the other day and it seems to almost not exsist.

Metroid (the ones i found were all by the same artist)
Disgaea
Metal Slug (fio x mars people plox)

Oreimo, specifically Kirino. I've read everything many times (apart from that guro one), I need moar. Hopefully comiket will bring more because season 2.

This, there are only a few good doujins.